Pulse or digital communications – Transceivers
Reexamination Certificate
1999-02-19
2004-07-13
Liu, Shuwang (Department: 2734)
Pulse or digital communications
Transceivers
C375S222000, C375S356000, C375S376000, C327S147000, C327S156000
Reexamination Certificate
active
06763060
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a communication system comprising a network of interconnected transceivers and associated digital systems and, more particularly, to mechanisms for selectively clocking the digital systems, bypassing data from being routed through the digital systems, or for reducing power consumption within transceivers and digital systems depending on whether data is received by the transceiver, and/or whether the transceivers are locked in sync with the data.
2. Description of the Related Art
Communication systems are generally well-known as containing at least two nodes interconnected by a communication line. Each node may include both a transmitter and a receiver, generally referred to as a “transceiver”. The transceiver provides an interface between signals sent over the communication line and a digital system which operates upon that signal in the digital domain.
A set of nodes interconnected by a communication line can be referred to as a communication network. A transmitter within one node can transmit a signal to one or more receivers in various nodes across the network. In high speed applications, the signal transmitted across the network can contain instructions and/or data, which conceivably could be audio data, video data, or both, and therefore the network may be considered a multi-media network. The transfer rate of multi-media signals is generally quite high and therefore requires a relatively high speed communication line, a suitable line being an optical fiber, for example.
If an optical fiber is used, then an interface which converts light energy to an electrical signal recognized by each transceiver is needed. That interface is generally a photosensor at the receive end of the communication line, or a light emitting diode at the transmit end. The interface is therefore an optical interface and therefore the transceiver can be considered a fiber optic transceiver. It is believed that most conventional fiber optic transceivers generally encompass elements which perform light/voltage conversion and nothing else. The system associated with each transceiver may employ both an analog and a digital section which perform manipulation of the received signal, processes that signal, and thereafter presents a transmitted signal compatible with signals forwarded across the optical fiber. Accordingly, a conventional, optical multi-media network typically employs a rather simplistic fiber optic transceiver, and a digital processing system, at each node of the network.
The digital system may be called upon not only to process the signal preferably in real-time, but also to process those signals synchronously. Therefore, conventional digital systems not only require a receiver with accurate amplification and data detection, but further utilize a phase-locked loop (“PLL”) useful in recovering a clocking signal from the received data. If the amplifiers and data detecting circuits at the receive end, drivers at the transmit end, and the PLL clock recovery circuits impute noise to, or receive noise from, the digital core of the digital processor, then data detection, clock recovery, data transmittal, and generalized data processing may be adversely affected. It would be desirable to minimize the cross talk between the digital processing core and the incoming data detection, clock recovery, and outgoing data driving circuits. Digital signal transitions, and/or latching circuits operating on those transitions, can oftentimes induce significant amounts of noise upon the power and ground conductors extending across the digital system to provide power and ground to the more sensitive clock and data recovery circuits, as well as the data transmit driver.
In addition to minimizing noise susceptibility of the sensing circuits, it would also be of benefit to provide power management to at least a portion of those circuits. In this manner, a low-power application can be realized as a significant improvement to conventional multi-media communication networks. Coupled with noise isolation and power management, the sensing portion of each node should also be made immediately responsive to the data signal forwarded from the network master. In this fashion, the slave nodes can recover a clocking signal in parallel and concurrent with each other so that the clocking signal is available as soon as possible to the corresponding digital systems.
SUMMARY OF THE INVENTION
The problems outlined above are in large part solved by an improved multi-media communication system. The communication system includes a set of nodes, wherein each node involves a transceiver interface and a digital system. The transceiver is coupled between the communication line and a corresponding digital system, and is used to modify the transmission format and/or protocol into a sequence of bits recognized by one or more digital systems within corresponding nodes. The transceiver is purposely placed on one or more monolithic substrates separate from a substrate bearing a digital system. The sensitive sensing and driving circuits, as well as the clock recovery PLL, may be embodied upon the transceiver separate from the corresponding digital system, and the noise induced by that system.
The present transceiver includes both a receiver and a transmitter. The receiver senses data transmitted across the communication line and performs conditioning and amplification to that signal before transferring it to the digital system for processing. Additionally, the receiver may include a PLL which recovers a clock from the received signal, and uses the recovered clocking signal to synchronize operations within the corresponding digital system. Of benefit, the number of conductors which link the transceiver and corresponding digital system is minimized as, for example, a data output conductor, a clocking/status signal output conductor, power, and ground. The power and ground conductors may be used to apply a common VDD and VSS supplies between the transceiver and corresponding digital system. It is noted, however, if a common power and ground supply is not needed, then only two conductors need be employed between the receiver of the transceiver and the respective digital system.
The sensing circuitry within the receiver generally operates at speeds matching the incoming data. For example, if the data rate of the incoming signal, and therefore the operating speed of the sensing circuitry, is several Mbits/second, or more preferably 50 Mbaud or greater, then the power consumed by the sensing circuitry can be rather substantial. Instead of maintaining power to the sensing circuitry during times when a signal is not present on the communication line, the receiver utilizes an activity detector which de-couples power to the sensing circuit in times when data is not present on the receiver receive port. In this manner, the present transceiver maintains power to power consumptive devices only when an input signal is present upon the receive port. During all other times, the power consumptive amplifiers, comparators, and clock recovery circuits (i.e., PLL) are powered down. Thus, a multi-media network employing the present transceivers can advantageously be placed in a low power environment, or an environment in which power is drawn from a portable power supply, such as a battery. For example, the multi-media network can be used in an automotive application, where audio, video, or generalized traffic information, are being sent between digital processors arranged throughout the automobile. Such processors include, for example, speech encoders/decoders, video/audio processors, video monitors, audio amplifiers (and associated speakers), sensors, calculators, computers, and FM/AM tuners, all of which can be placed on-board existing automobiles to enhance both usability and performance of the automobile. In an automotive environment, it is desirable that the communication line be fiber optic, and the light-transmissive data be isolated from each transceiver by photosensors and LEDs. Opti
Conley & Rose, P.C.
Daffer Kevin L.
Liu Shuwang
Oasis Silicon Systems
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